Reeling from a surge in battlefield losses, Afghanistan's military is overhauling its war strategy against the Taliban to concentrate forces around the most critical areas like Kabul and other cities, border crossings and vital infrastructure, Afghan and US officials say.

The politically perilous strategy will inevitably cede territory to Taliban insurgents. But officials say it appears to be a military necessity as over-stretched Afghan troops try to prevent the loss of provincial capitals, which could deeply fracture the country.

The consolidation of forces, which has been publicly acknowledged but not reported in such detail before, coincides with the US military withdrawal ahead of a formal end to the military mission on Aug 31, on orders from President Joe Biden.

Taliban insurgents are gaining control of more and more territory, which the Pentagon estimated on Wednesday now extends to over half of Afghanistan's district centres. The Taliban are also putting pressure on the outskirts of half of the provincial capitals, trying to isolate them.

US intelligence assessments have warned that...